Because it can be too time consuming and costly to go back to the RTL after synthesis, you can make changes in the netlist as follows.
- Select
- Select Cells from the Find drop-down list.
- Under Properties, set PRIMITIVE_TYPE to BMEM.BRAM.
- Make sure that Search Hierarchy is selected, as shown in the following figure.
- Click OK.
The Find Results window opens.
to open the Find dialog box, as shown in the following figure. - Select the Show Search button on the toolbar menu of the Find Results window.
- Search for
ingressLoop
, and select the following cell: fftEngine/fftInst/ingressLoop[7].ingressFifo/In the Properties tab of the Cell Properties window, you can see the DOA_REG and DOB_REG are set to zero, indicating that the output registers are disabled.
- Generate a custom timing report from this cell directly from the Tcl
Console. The Tcl command to enter
is:
report_timing -from [get_cells fftEngine/fftInst/ingressLoop[7].ingressFifo/ buffer_fifo/infer_fifo.block_ram_performance.fifo_ram_reg]
Tip: You can copy and paste the cell name from the General tab of the Cell Properties window into the Tcl Console. - In the upper-right corner of the Tcl Console, click the Maximize button to maximize the window and better view the timing report.
- In the data path section of the report, 1.800 ns is added by this RAMB.
- Restore the Tcl Console to its normal size.
- In the Properties tab of the Cell Properties window, select the DOA_REG and
DOB_REG properties for this cell and change their values for "0" to "1."
You can see two
set_property
commands run in the Tcl Console.set_property DOA_REG {1} [get_cells {fftEngine/fftInst/ingressLoop[7].ingressFifo/ buffer_fifo/infer_fifo.block_ram_performance.fifo_ram_reg}] set_property DOB_REG {1} [get_cells {fftEngine/fftInst/ingressLoop[7].ingressFifo /buffer_fifo/infer_fifo.block_ram_performance.fifo_ram_reg}]
- Run the timing report from the selected cell. The Tcl command to enter
is:
report_timing -from [get_cells fftEngine/fftInst/ingressLoop[7].ingressFifo /buffer_fifo/infer_fifo.block_ram_performance.fifo_ram_reg]
- Notice that the data path delay for the RAM is now 0.622 ns.